1. Technical Field
This invention relates to lossless data transformation, such as compression and decompression. More particularly, the invention concerns lossless transformation utilizing adaptive compression, multidimensional prediction, and/or multi-symbol decoding.
2. Description of the Prior Art
Video data is typically encoded in large blocks of memory. Even a single video frame can require megabytes to describe it. Video data requires large amounts of memory to store and high communication bandwidths to transfer. It therefore is highly advantageous to compress video data. However, some compression methods lose information in the process.
Some applications can tolerate various degrees of loss, but still others require loss-less compression.
The typical loss-less video data compression methods use differential pulse code modulation (DPCM). A current pixel value is replaced by the difference between it and the previous pixel. Since pixel values change rather slowly along scan lines, the difference values will near zero, making compression algorithms particularly effective. However, many times, the slow change between pixel values occurs in vertical or diagonal bands. Techniques that can only take advantage of horizontal bands in the image are compromised.
Huffman coding can be used to compress real-time video data. A Huffman-tree is built and the tree is used to recode the data. The basic idea is that frequently occurring video codes are replaced by a Huffman code that requires fewer bits. Occasional video codes that occur infrequently are described with Huffman codes that require more bits than the video code itself. In spite of this, the mere use of Huffman codes does result in an overall gain in compression.
In spite of the advantages provided by Huffman coding and other advancements in the field of data compression, the present inventor(s) has worked to develop enhancements, improvements, and solutions to various problems in the related field.